In vivo therapeutic potential of mesenchymal stromal cells depends on the source and the isolation procedure

Role of Mesenchymal Stem/Stromal Cells in Head and Neck Cancer-Regulatory Mechanisms of Tumorigenic and Immune Activity, Chemotherapy Resistance, and Therapeutic Benefits of Stromal Cell-Based Pharmacological Strategies

Head and neck cancer (HNC) entails a heterogenous neoplastic disease that arises from the mucosal epithelium of the upper respiratory system and the gastrointestinal tract. It is characterized by high morbidity and mortality, being the eighth most common cancer worldwide. It is believed that the mesenchymal/stem stromal cells (MSCs) present in the tumour milieu play a key role in the modulation of tumour initiation, development and patient outcomes; they also influence the resistance to cisplatin-based chemotherapy, the gold standard for advanced HNC. MSCs are multipotent, heterogeneous and mobile cells. Although no MSC-specific markers exist, they can be recognized based on several others, such as CD73, CD90 and CD105, while lacking the presence of CD45, CD34, CD14 or CD11b, CD79α, or CD19 and HLA-DR antigens; they share phenotypic similarity with stromal cells and their capacity to differentiate into other cell types. In the tumour niche, MSC populations are characterized by cell quiescence, self-renewal capacity, low reactive oxygen species production and the acquisition of epithelial-to-mesenchymal transition properties. They may play a key role in the process of acquiring drug resistance and thus in treatment failure. The present narrative review examines the links between MSCs and HNC, as well as the different mechanisms involved in the development of resistance to current chemo-radiotherapies in HNC. It also examines the possibilities of pharmacological targeting of stemness-related chemoresistance in HNSCC. It describes promising new strategies to optimize chemoradiotherapy, with the potential to personalize patient treatment approaches, and highlights future therapeutic perspectives in HNC.

Research hotspots and emerging trends of mesenchymal stem cells in cardiovascular diseases: a bibliometric-based visual analysis

Background

Mesenchymal stem cells (MSCs) have important research value and broad application prospects in cardiovascular diseases (CVDs). However, few bibliometric analyses on MSCs in cardiovascular diseases are available. This study aims to provide a thorough review of the cooperation and influence of countries, institutions, authors, and journals in the field of MSCs in cardiovascular diseases, with the provision of discoveries in the latest progress, evolution paths, frontier research hotspots, and future research trends in the regarding field.

Methods

The articles related to MSCs in cardiovascular diseases were retrieved from the Web of Science. The bibliometric study was performed by CiteSpace and VOSviewer, and the knowledge map was generated based on data obtained from retrieved articles.

Results

In our study, a total of 4,852 publications launched before August 31, 2023 were accessed through the Web of Science Core Collection (WoSCC) database via our searching strategy. Significant fluctuations in global publications were observed in the field of MSCs in CVDs. China emerged as the nation with the largest number of publications, yet a shortage of high-quality articles was noted. The interplay among countries, institutions, journals and authors is visually represented in the enclosed figures. Importantly, current research trends and hotspots are elucidated. Cluster analysis on references has highlighted the considerable interest in exosomes, extracellular vesicles, and microvesicles. Besides, keywords analysis revealed a strong emphasis on myocardial infarction, therapy, and transplantation. Treatment methods-related keywords were prominent, while keywords associated with extracellular vesicles gathered significant attention from the long-term perspective.

Conclusion

MSCs in CVDs have become a topic of active research interest, showcasing its latent value and potential. By summarizing the latest progress, identifying the research hotspots, and discussing the future trends in the advancement of MSCs in CVDs, we aim to offer valuable insights for considering research prospects.

Media matters: culture medium-dependent hypervariable phenotype of mesenchymal stromal cells

BACKGROUND

Despite a long history of investigation and sustained efforts in clinical testing, the number of market authorisations for mesenchymal stromal cell (MSC) therapies remains limited, with none approved by the United States Food and Drug Administration. Several barriers are impeding the clinical progression of MSC therapies, to the forefront of these is a lack of standardised manufacturing protocols which is further compounded by an absence of biologically meaningful characterisation and release assays. A look at clinical trial registries demonstrates the diversity of MSC expansion protocols with variabilities in cell source, isolation method and expansion medium, among other culture variables, making it extraordinarily difficult to compare study outcomes. Current identification and characterisation standards are insufficient; they are not specific to MSCs and do not indicate cell function or therapeutic action.

METHODS

This work analysed the influence of five widely used culture media formulations on the colony-forming potential, proliferation kinetics, trilineage differentiation potential and immunomodulatory potential of human bone marrow-derived MSCs (BM-MSCs). The surface marker expression profiles were also characterised using a high-content flow cytometry screening panel of 243 markers.

RESULTS

Significant differences in the biological attributes of BM-MSCs including clonogenicity, proliferation, differentiation propensity and immunomodulatory capacity were revealed in response to the composition of the culture medium. Despite their biological differences, all cell preparations uniformly and strongly expressed the standard positive markers proposed for BM-MSCs: CD73, CD90 and CD105. Immunophenotypic profiling revealed that the culture medium also had a significant influence on the surface proteome, with one-third of tested markers exhibiting variable expression profiles. Principal component analysis demonstrated that BM-MSCs isolated and expanded in a proprietary xeno- and serum-free medium displayed the most consistent cell phenotypes with little variability between donors compared to platelet lysate and foetal bovine serum-containing media.

CONCLUSIONS

These data suggest that media composition has a highly significant impact on the biological attributes of MSCs, but standard surface marker tests conceal these differences. The results indicate a need for (1) standardised approaches to manufacturing, with an essential focus on defined media and (2) new biologically relevant tests for MSC characterisation and product release.

Mesenchymal Stem Cells: Their Role in the Tumor Microenvironment

Mesenchymal stem cells (MSCs) have been seen for years as great candidates for treating different diseases and an alternative to embryonic stem cells due to their differentiation capacity in vitro. More recent research has focused on their ability to modulate the immune response and regeneration at sites associated with inflammation, activities attributable to the release of trophic factors into the extracellular medium, a set of components known as the secretome. It has been possible to demonstrate the presence of these cells within the tumor microenvironment, which is associated with their tropism for sites of inflammation; however, their role here needs to be clarified. In different investigations, the feasibility of using MSCs or their secretome to treat cancer has been sought, with these results being ambiguous. It has been described that MSCs can be activated and present various phenotypes, which could explain the divergence in their action; however, these activation mechanisms and the different phenotypes still need to be well known. This review explores MSCs and their use in regenerative medicine with a targeted approach to cancer. Impact Statement This text addresses the diverging findings on the role of mesenchymal stem cells in the tumor microenvironment and discrepancies on the use of these cells as cancer treatment, separating the direct use of the cells from the use of the secretome. Multiple authors refer equally to the cells and their secretome to conclude on the positive or negative outcome, without taking into consideration how the cells are affected by their surroundings.

Human Mesenchymal Stromal Cells Derived from Perinatal Tissues: Sources, Characteristics and Isolation Methods

Mesenchymal stromal/stem cells (MSCs) derived from perinatal tissues have become indispensable sources for clinical applications due to their superior properties, ease of accessibility and minimal ethical concerns. MSCs isolated from different placenta (PL) and umbilical cord (UC) compartments exhibit great potential for stem cell-based therapies. However, their biological activities could vary due to tissue origins and differences in differentiation potentials. This review provides an overview of MSCs derived from various compartments of perinatal tissues, their characteristics and current isolation methods. Factors affecting the yield and purity of MSCs are also discussed as they are important to ensure consistent and unlimited supply for regenerative medicine and tissue engineering.

Ischemic wound revascularization by the stromal vascular fraction relies on host-donor hybrid vessels

Nonhealing wounds place a significant burden on both quality of life of affected patients and health systems. Skin substitutes are applied to promote the closure of nonhealing wounds, although their efficacy is limited by inadequate vascularization. The stromal vascular fraction (SVF) from the adipose tissue is a promising therapy to overcome this limitation. Despite a few successful clinical trials, its incorporation in the clinical routine has been hampered by their inconsistent results. All these studies concluded by warranting pre-clinical work aimed at both characterizing the cell types composing the SVF and shedding light on their mechanism of action. Here, we established a model of nonhealing wound, in which we applied the SVF in combination with a clinical-grade skin substitute. We purified the SVF cells from transgenic animals to trace their fate after transplantation and observed that it gave rise to a mature vascular network composed of arteries, capillaries, veins, as well as lymphatics, structurally and functionally connected with the host circulation. Then we moved to a human-in-mouse model and confirmed that SVF-derived endothelial cells formed hybrid human-mouse vessels, that were stabilized by perivascular cells. Mechanistically, SVF-derived endothelial cells engrafted and expanded, directly contributing to the formation of new vessels, while a population of fibro-adipogenic progenitors stimulated the expansion of the host vasculature in a paracrine manner. These data have important clinical implications, as they provide a steppingstone toward the reproducible and effective adoption of the SVF as a standard care for nonhealing wounds.

Mesenchymal stem cells for regenerative medicine in central nervous system

Mesenchymal stem cells (MSCs) are multipotent stem cells, whose paracrine and immunomodulatory potential has made them a promising candidate for central nervous system (CNS) regeneration. Numerous studies have demonstrated that MSCs can promote immunomodulation, anti-apoptosis, and axon re-extension, which restore functional neural circuits. The therapeutic effects of MSCs have consequently been evaluated for application in various CNS diseases including spinal cord injury, cerebral ischemia, and neurodegenerative disease. In this review, we will focus on the research works published in the field of mechanisms and therapeutic effects of MSCs in CNS regeneration.

Hyperthermia-stimulated tonsil-mesenchymal stromal cells suppress hematological cancer cells through downregulation of IL-6

There are contradictory reports on the use of mesenchymal stromal cells (MSCs) in cancer therapy. Variable outcomes have been associated with several factors including cancer pathology, experimental procedure, MSC source tissue, and individual genetic differences. It is also known that MSCs exert their therapeutic effects with various paracrine factors released from these cells. The profiles of the factors released from MSCs are altered by heat shock, hypoxia, oxidative stress, starvation or various agents such as inflammatory cytokines, and their therapeutic potential is affected. In this study, the antitumor potential of conditioned media (CM), which contains paracrine factors, of mild hyperthermia-stimulated mesenchymal stromal cells derived from lymphoid organ tonsil tissue (T-MSC) was investigated in comparison with CM obtained from T-MSCs grew under normal culture conditions. CM was obtained from T-MSCs that were successfully isolated from palatine tonsil tissue and characterized. The cytotoxic effect of CM on the growth of hematological cancer cell lines at different concentrations (1:1 and 1:2) was demonstrated by methylthiazoldiphenyl-tetrazolium bromide analysis. In addition, the apoptotic effect of T-MSC-CM treatment was evaluated on the cancer cells using Annexin-V/PI detection method by flow cytometry. The pro/anti-apoptotic and cytokine-related gene expressions were also analyzed by real-time polymerase chain reaction post T-MSC-CM treatment. In conclusion, we demonstrated that the factors released from hyperthermia-stimulated T-MSCs induced apoptosis in hematological cancer cell lines in a dose-dependent manner. Importantly, our results at the transcriptional level support that the factors and cytokines released from hyperthermia-stimulated T-MSC may exert antitumoral effects in cancer cells by downregulation of IL-6 that promotes tumorigenesis. These findings reveal that T-MSC-CM can be a powerful cell-free therapeutical strategy for cancer therapy.

Mesenchymal Stromal Cells Combined With Elastin-Like Recombinamers Increase Angiogenesis In Vivo After Hindlimb Ischemia

Hindlimb ischemia is an unmet medical need, especially for those patients unable to undergo vascular surgery. Cellular therapy, mainly through mesenchymal stromal cell (MSC) administration, may be a potentially attractive approach in this setting. In the current work, we aimed to assess the potential of the combination of MSCs with a proangiogenic elastin-like recombinamer (ELR)–based hydrogel in a hindlimb ischemia murine model. Human bone marrow MSCs were isolated from four healthy donors, while ELR biomaterials were genetically engineered. Hindlimb ischemia was induced through ligation of the right femoral artery, and mice were intramuscularly injected with ELR biomaterial, 0.5 × 10⁶ MSCs or the combination, and also compared to untreated animals. Tissue perfusion was monitored using laser Doppler perfusion imaging. Histological analysis of hindlimbs was performed after hematoxylin and eosin staining. Immunofluorescence with anti–human mitochondria antibody was used for human MSC detection, and the biomaterial was detected by elastin staining. To analyze the capillary density, immunostaining with an anti–CD31 antibody was performed. Our results show that the injection of MSCs significantly improves tissue reperfusion from day 7 (p = 0.0044) to day 21 (p = 0.0216), similar to the infusion of MSC + ELR (p = 0.0038, p = 0.0014), without significant differences between both groups. After histological evaluation, ELR hydrogels induced minimal inflammation in the injection sites, showing biocompatibility. MSCs persisted with the biomaterial after 21 days, both in vitro and in vivo. Finally, we observed a higher blood vessel density when mice were treated with MSCs compared to control (p<0.0001), but this effect was maximized and significantly different to the remaining experimental conditions when mice were treated with the combination of MSCs and the ELR biomaterial (p < 0.0001). In summary, the combination of an ELR-based hydrogel with MSCs may improve the angiogenic effects of both strategies on revascularization of ischemic tissues.

Factors influencing mesenchymal stromal cells in in vitro cellular models to study retinal pigment epithelial cell rescue

Mesenchymal stromal cells (MSC) stop or slow retinal pigment epithelium (RPE) and neuroretina (NR) degeneration by paracrine activity in oxidative stress-induced retinal degenerative diseases. However, it is mandatory to develop adequate in vitro models that allow testing new treatment strategies against oxidative stress before performing in vivo studies. The viable double- and triple-layered setups are composed of separate layers of NR, MSC, and RPE (NR-MSC-RPE, NR-RPE, MSC-RPE) partially mimic in vivo retinal conditions. In this study, the paracrine neuroprotective effect of each setup's microenvironment on hydrogen peroxide (H₂O₂)-stressed was compared with unstressed RPE cells. RPE cell proliferation viability was assessed on day 1, 3, and 6 using Alamar Blue® (10%), MTT (10%) and a cell viability/cytotoxicity assay kit followed by data analysis. The results showed that RPE cells, highly viable (> 90%) in mixed medium of DMEM and neurobasal A (1:1), lost 50% viability on exposure to 400 µM of H₂O₂ (P < 0.05). The unexposed groups differed significantly from exposed groups for RPE cell growth (RPE and [Formula: see text]RPE (P < 0.0001), NR-MSC-RPE, and NR-MSC-[Formula: see text]RPE (P < 0.05), NR-RPE and NR-[Formula: see text]RPE (P < 0.01), and MSC-RPE and MSC-[Formula: see text]RPE (P < 0.01). NR-[Formula: see text]RPE and NR-RPE supported RPE cell proliferation viability better than other setups (P < 0.01) and RPE cells proliferated 0.49-fold more in NR-MSC-[Formula: see text]RPE than NR-MSC-RPE. Thus, NR and MSC presence improved significantly each setup's microenvironment for cell rescue, nevertheless, each setup also showed limitations for its use as an in vitro study tool. Health of microenvironment of such setups depends on many factors including cell-secreted trophic factors.

Interaction of Neural Stem Cells (NSCs) and Mesenchymal Stem Cells (MSCs) as a Promising Approach in Brain Study and Nerve Regeneration

Rapid developments in stem cell research in recent years have provided a solid foundation for their use in medicine. Over the last few years, hundreds of clinical trials have been initiated in a wide panel of indications. Disorders and injuries of the nervous system still remain a challenge for the regenerative medicine. Neural stem cells (NSCs) are the optimal cells for the central nervous system restoration as they can differentiate into mature cells and, most importantly, functional neurons and glial cells. However, their application is limited by multiple factors such as difficult access to source material, limited cells number, problematic, long and expensive cultivation in vitro, and ethical considerations. On the other hand, according to the available clinical databases, most of the registered clinical trials involving cell therapies were carried out with the use of mesenchymal stem/stromal/signalling cells (MSCs) obtained from afterbirth or adult human somatic tissues. MSCs are the multipotent cells which can also differentiate into neuron-like and glia-like cells under proper conditions in vitro; however, their main therapeutic effect is more associated with secretory and supportive properties. MSCs, as a natural component of cell niche, affect the environment through immunomodulation as well as through the secretion of the trophic factors. In this review, we discuss various therapeutic strategies and activated mechanisms related to bilateral MSC–NSC interactions, differentiation of MSCs towards the neural cells (subpopulation of crest-derived cells) under the environmental conditions, bioscaffolds, or co-culture with NSCs by recreating the conditions of the neural cell niche.

Adipose-Derived Stem Cells From Patients With Ulcerative Colitis Exhibit Impaired Immunosuppressive Function

Adipose-derived stem cells (ADSCs) are able to modulate the immune response and are used for treating ulcerative colitis (UC). However, it is possible that ADSCs from patients with inflammatory or autoimmune disorders may show defective immunosuppression. We investigated the use of ADSCs from UC patients for autologous cell treatment, specifically, ADSCs from healthy donors (H-ADSCs) and UC patients (P-ADSCs) in terms of various functions, including differentiation, proliferation, secretion, and immunosuppression. The efficacy of P-ADSCs for treating UC was examined in mouse models of acute or chronic colitis. Both H-ADSCs and P-ADSCs were similar in cell morphology, size, adipogenic differentiation capabilities, and cell surface markers. We found that P-ADSCs had lower proliferative capacity, cloning ability, and osteogenic and chondrogenic differentiation potential than H-ADSCs. P-ADSCs exhibited a diminished capacity to inhibit peripheral blood mononuclear cell proliferation, suppress CD25 and CD69 marker expression, decrease the production of inflammation-associated cytokines interferon-γ and tumor necrosis factor-α, and reduce their cytotoxic effect on A549 cells. When primed with inflammatory cytokines, P-ADSCs secreted lower levels of prostaglandin E2, indoleamine 2, 3-dioxygenase, and tumor necrosis factor-α–induced protein 6, which mediated their reduced immunopotency. Moreover, P-ADSCs exhibited weaker therapeutic effects than H-ADSCs, determined by disease activity, histology, myeloperoxidase activity, and body weight. These findings indicate that the immunosuppressive properties of ASCs are affected by donor metabolic characteristics. This study shows, for the first time, the presence of defective ADSC immunosuppression in UC, indicating that autologous transplantation of ADSCs may be inappropriate for patients with UC.

Impact of allogeneic feline uterine-derived mesenchymal stromal cell intravenous treatment on renal function of nephrectomized cats with chronic kidney disease

Chronic kidney disease (CKD) is a common condition and leading cause of mortality in cats. Mesenchymal stromal cells (MSCs) may have a therapeutic effect on CKD. The aim of this pilot study was to determine efficacy of systemically-administered allogeneic uterine tissue-derived MSCs (UMSCs) in cats with CKD. Eighteen renal-compromised, unilaterally nephrectomized cats received two doses of 3 × 10⁷ allogeneic UMSCs given intravenously (IV) with a 2-week dose interval. The primary endpoint was renal function, with treatment success defined by a 20% increase in glomerular filtration rate (GFR; iohexol clearance) and/or a 20% decrease in plasma creatinine in 50% of the cats. Secondary endpoints included diet and water consumption, body weight, urine characteristics, and adverse events. Treatment was well tolerated and associated with a statistically meaningful increase in GFR on Days 13, 28, 57, 99, 121 and 182, compared with baseline (P < 0.0001 for Days 13 to 99 inclusive; P = 0.0029 and P = 0.0225 for Days 121 and 182, respectively). Greater than 50% of the cats demonstrated a 20% increase in GFR on all days except Day 150, at which point GFR measurements were consistently above baseline. Statistically meaningful increases in diet and water consumption were observed. Substantial improvements in GFR were observed throughout the six-month evaluation period (excluding Day 150) in more than 50% of cats, thereby meeting the primary endpoint. Therefore, this IV-administered, allogeneic cellular therapy may support both renal function and clinical status of cats with CKD.

An overview of mesenchymal stem cells and their potential therapeutic benefits in cancer therapy

There has been increased interest in using stem cells for regenerative medicine and cancer therapy in the past decade. Mesenchymal stem cells (MSCs) are among the most studied stem cells due to their unique characteristics, such as self-renewal and developmental potency to differentiate into numerous cell types. MSC use has fewer ethical challenges compared with other types of stem cells. Although a number of studies have reported the beneficial effects of MSC-based therapies in treating various diseases, their contribution to cancer therapy remains controversial. The behaviour of MSCs is determined by the interaction between intrinsic transcriptional genes and extrinsic environmental factors. Numerous studies continue to emerge, as there is no denying the potential of MSCs to treat a wide variety of human afflictions. Therefore, the present review article provided an overview of MSCs and their differences compared with embryonic stem cells, and described the molecular mechanisms involved in maintaining their stemness. In addition, the article examined the therapeutic application of stem cells in the field of cancer. The present article also discussed the current divergent roles of MSCs in cancer therapy and the future potential in this field.

Mesenchymal stromal cells as carriers of IL-12 reduce primary and metastatic tumors of murine melanoma

Due to immunosuppressive properties and confirmed tropism towards cancer cells mesenchymal stromal cells (MSC) have been used in many trials. In our study we used these cells as carriers of IL-12 in the treatment of mice with primary and metastatic B16-F10 melanomas. IL-12 has confirmed anti-cancer activity, induces a strong immune response against cancer cells and acts as an anti-angiogenic agent. A major limitation of the use of IL-12 in therapy is its systemic toxicity. The aim of the work was to develop a system in which cytokine may be administered intravenously without toxic side effects. In this study MSC were used as carriers of the IL-12. We confirmed antitumor effectiveness of the cells secreting IL-12 (MSC/IL-12) in primary and metastatic murine melanoma models. We observed inhibition of tumor growth and a significant reduction in the number of metastases in mice after MSC/IL-12 administration. MSC/IL-12 decreased vascular density and increased the number of anticancer M1 macrophages and CD8⁺ cytotoxic T lymphocytes in tumors of treated mice. To summarize, we showed that MSC are an effective, safe carrier of IL-12 cytokine. Administered systemically they exert therapeutic properties of IL-12 cytokine without toxicity. Therapeutic effect may be a result of pleiotropic (proinflammatory and anti-angiogenic) properties of IL-12 released by modified MSC.

Stem Cell Therapies for Progressive Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterized by demyelination and axonal degeneration. MS patients typically present with a relapsing-remitting (RR) disease course, manifesting as sporadic attacks of neurological symptoms including ataxia, fatigue, and sensory impairment. While there are several effective disease-modifying therapies able to address the inflammatory relapses associated with RRMS, most patients will inevitably advance to a progressive disease course marked by a gradual and irreversible accrual of disabilities. Therapeutic intervention in progressive MS (PMS) suffers from a lack of well-characterized biological targets and, hence, a dearth of successful drugs. The few medications approved for the treatment of PMS are typically limited in their efficacy to active forms of the disease, have little impact on slowing degeneration, and fail to promote repair. In looking to address these unmet needs, the multifactorial therapeutic benefits of stem cell therapies are particularly compelling. Ostensibly providing neurotrophic support, immunomodulation and cell replacement, stem cell transplantation holds substantial promise in combatting the complex pathology of chronic neuroinflammation. Herein, we explore the current state of preclinical and clinical evidence supporting the use of stem cells in treating PMS and we discuss prospective hurdles impeding their translation into revolutionary regenerative medicines.

Genetically-Modified Stem Cell in Regenerative Medicine and Cancer Therapy; A New Era

Recently, genetic engineering by various strategies to stimulate gene expression in a specific and controllable mode is a speedily growing therapeutic approach. Genetic modification of human stem or progenitor cells, such as embryonic stem cells (ESCs), neural progenitor cells (NPCs), mesenchymal stem/stromal cells (MSCs), and hematopoietic stem cells (HSCs) for direct delivery of specific therapeutic molecules or genes has been evidenced as an opportune plan in the context of regenerative medicine due to their supported viability, proliferative features, and metabolic qualities. On the other hand, a large number of studies have investigated the efficacy of modified stem cells in cancer therapy using cells from various sources, disparate transfection means for gene delivery, different transfected yields, and wide variability of tumor models. Accordingly, cell-based gene therapy holds substantial aptitude for the treatment of human malignancy as it could relieve signs or even cure cancer succeeding expression of therapeutic or suicide transgene products; however, there exist inconsistent results in this regard. Herein, we deliver a brief overview of stem cell potential to use in cancer therapy and regenerative medicine and importantly discuss stem cells based gene delivery competencies to stimulate tissue repair and replacement in concomitant with their potential to use as an anti-cancer therapeutic strategy, focusing on the last two decades in vivo studies.

Mouse Bone Marrow-derived Microglia-like Cells Secrete Transforming Growth Factor-β1 and Promote Microglial Aβ Phagocytosis and Reduction of Brain Aβ

Accumulation of amyloid-β (Aβ) in brain tissue contributes to the pathophysiology of Alzheimer's disease (AD). We recently reported that intrahippocampal transplantation of mouse bone marrow-derived microglia-like (BMDML) cells suppresses brain amyloid pathology and cognitive impairment in a mouse model of AD. How these transplanted cells interact with resident microglia remains unknown. In the present study, we evaluated the effects of cytokines secreted from mouse BMDML cells on cultured mouse microglia. Conditioned medium from BMDML cells increased microglial Aβ phagocytosis. High levels of transforming growth factor-β1 (TGF-β1) were present in the conditioned medium, and BMDML cells and microglia expressed Tgf-β1 mRNA and TGF-β receptor type 1 (TGF-βR1) protein, respectively. BMDML conditioned medium also induced microglial Smad2/3 phosphorylation. A TGF-βR1 inhibitor suppressed Smad2/3 phosphorylation and promotion of microglial Aβ phagocytosis induced by conditioned medium. Recombinant mouse TGF-β1 similarly increased microglial Aβ phagocytosis and induced Smad2/3 phosphorylation, which were suppressed by the TGF-βR1 inhibitor. Brain TGF-β1 levels and resident microglial TGF-β1R expression were increased by intrahippocampal injection of BMDML cells in a mouse model of AD. Cotreatment with the TGF-βR1 inhibitor suppressed the ability of transplanted BMDML cells to increase microglial TGF-β1R expression and decrease hippocampal Aβ levels. Taken together, these findings suggested that transplanted BMDML cells secreted TGF-β1 to stimulate Aβ phagocytosis by resident microglia and decrease brain Aβ pathology.

Mesenchymal Stromal Cell-Based Therapies as Promising Treatments for Muscle Regeneration After Snakebite Envenoming

Snakebite envenoming is a global neglected disease with an incidence of up to 2.7 million new cases every year. Although antivenoms are so-far the most effective treatment to reverse the acute systemic effects induced by snakebite envenoming, they have a limited therapeutic potential, being unable to completely neutralize the local venom effects. Local damage, such as dermonecrosis and myonecrosis, can lead to permanent sequelae with physical, social, and psychological implications. The strong inflammatory process induced by snake venoms is associated with poor tissue regeneration, in particular the lack of or reduced skeletal muscle regeneration. Mesenchymal stromal cells (MSCs)-based therapies have shown both anti-inflammatory and pro-regenerative properties. We postulate that using allogeneic MSCs or their cell-free products can induce skeletal muscle regeneration in snakebite victims, improving all the three steps of the skeletal muscle regeneration process, mainly by anti-inflammatory activity, paracrine effects, neovascularization induction, and inhibition of tissue damage, instrumental for microenvironment remodeling and regeneration. Since snakebite envenoming occurs mainly in areas with poor healthcare, we enlist the principles and potential of MSCs-based therapies and discuss regulatory issues, good manufacturing practices, transportation, storage, and related-procedures that could allow the administration of these therapies, looking forward to a safe and cost-effective treatment for a so far unsolved and neglected health problem.

Cell-based strategies for IVD repair: clinical progress and translational obstacles

Intervertebral disc (IVD) degeneration is a major cause of low back pain, a prevalent and chronic condition that has a striking effect on quality of life. Currently, no approved pharmacological interventions or therapies are available that prevent the progressive destruction of the IVD; however, regenerative strategies are emerging that aim to modify the disease. Progress has been made in defining promising new treatments for disc disease, but considerable challenges remain along the entire translational spectrum, from understanding disease mechanism to useful interpretation of clinical trials, which make it difficult to achieve a unified understanding. These challenges include: an incomplete appreciation of the mechanisms of disc degeneration; a lack of standardized approaches in preclinical testing; in the context of cell therapy, a distinct lack of cohesion regarding the cell types being tested, the tissue source, expansion conditions and dose; the absence of guidelines regarding disease classification and patient stratification for clinical trial inclusion; and an incomplete understanding of the mechanisms underpinning therapeutic responses to cell delivery. This Review discusses current approaches to disc regeneration, with a particular focus on cell-based therapeutic strategies, including ongoing challenges, and attempts to provide a framework to interpret current data and guide future investigational studies.

Adipose-Derived Mesenchymal Stromal Cells in Regenerative Medicine: State of Play, Current Clinical Trials, and Future Prospects

Significance: Wound healing is a complex process involving pain and inflammation, where innervation plays a central role. Managing wound healing and pain remains an important issue, especially in pathologies such as excessive scarring (often leading to fibrosis) or deficient healing, leading to chronic wounds. Recent Advances: Advances in therapies using mesenchymal stromal cells offer new insights for treating indications that previously lacked options. Adipose-derived mesenchymal stromal cells (AD-MSCs) are now being used to a much greater extent in clinical trials for regenerative medicine. However, to be really valid, these randomized trials must imperatively follow strict guidelines such as consolidated standards of reporting trials (CONSORT) statement. Indeed, AD-MSCs, because of their paracrine activities and multipotency, have potential to cure degenerative and/or inflammatory diseases. Combined with their relatively easy access (from adipose tissue) and proliferation capacity, AD-MSCs represent an excellent candidate for allogeneic treatments. Critical Issues: The success of AD-MSC therapy may depend on the robustness of the biological functions of AD-MSCs, which requires controlling source heterogeneity and production processes, and development of biomarkers that predict desired responses. Several studies have investigated the effect of AD-MSCs on innervation, wound repair, or pain management separately, but systematic evaluation of how those effects could be combined is lacking. Future Directions: Future studies that explore how AD-MSC therapy can be used to treat difficult-to-heal wounds, underlining the need to thoroughly characterize the cells used, and standardization of preparation processes are needed. Finally, how this a priori easy-to-use cell therapy treatment fits into clinical management of pain, improvement of tissue healing, and patient quality of life, all need to be explored.

Therapeutic Effects of Lyophilized Conditioned-Medium Derived from Corneal Mesenchymal Stromal Cells on Corneal Epithelial Wound Healing

Objectives: The conditioned-medium derived from corneal mesenchymal stromal cells (cMSCs) has been shown to have wound healing and immunomodulatory effects in corneal injury models. Here, the therapeutic effects of lyophilized cMSC conditioned-medium were compared with fresh conditioned-medium. Methods: The epithelial wound healing effects of fresh and lyophilized cMSC conditioned-medium were compared with conditioned-medium from non-MSC cells (corneal epithelial cells) using scratch assay. To evaluate the anti-inflammatory effects of fresh and lyophilized cMSC conditioned-media, macrophages were stimulated by a Toll-Like Receptor (TLR) ligand followed by treatment with the conditioned-media and measuring the expression of inflammatory genes. In vivo wound healing effects of fresh and lyophilized cMSC conditioned-media were assessed in a murine model of cornea epithelial injury. Results: Both fresh and lyophilized cMSCs-derived conditioned-medium induced significantly faster closure of in vitro epithelial wounds compared to conditioned-medium from non-MSC cells (P < .0001). Treating stimulated macrophages with fresh or lyophilized cMSCs-derived conditioned-media significantly decreased the expression of inflammatory genes compared to control (P < .0001). Murine corneal epithelial wounds were healed by 87.6 ± 2.7% and 86.2 ± 4.6% following treatment with fresh and lyophilized cMSC conditioned-media, respectively, while the control was healed by 64.7 ± 16.8% (P < .05). Conclusion: Lyophilized cMSC-derived conditioned-medium is as effective as fresh conditioned-medium in promoting wound healing and modulating inflammation. The results of this study support the application of lyophilized cMSCs-derived conditioned-medium, which allows for more extended storage, as a promising non-invasive option in the treatment of corneal wounds.

Current Status and Future Prospects of Genome-Scale Metabolic Modeling to Optimize the Use of Mesenchymal Stem Cells in Regenerative Medicine

Mesenchymal stem cells are a promising source for externally grown tissue replacements and patient-specific immunomodulatory treatments. This promise has not yet been fulfilled in part due to production scaling issues and the need to maintain the correct phenotype after re-implantation. One aspect of extracorporeal growth that may be manipulated to optimize cell growth and differentiation is metabolism. The metabolism of MSCs changes during and in response to differentiation and immunomodulatory changes. MSC metabolism may be linked to functional differences but how this occurs and influences MSC function remains unclear. Understanding how MSC metabolism relates to cell function is however important as metabolite availability and environmental circumstances in the body may affect the success of implantation. Genome-scale constraint based metabolic modeling can be used as a tool to fill gaps in knowledge of MSC metabolism, acting as a framework to integrate and understand various data types (e.g., genomic, transcriptomic and metabolomic). These approaches have long been used to optimize the growth and productivity of bacterial production systems and are being increasingly used to provide insights into human health research. Production of tissue for implantation using MSCs requires both optimized production of cell mass and the understanding of the patient and phenotype specific metabolic situation. This review considers the current knowledge of MSC metabolism and how it may be optimized along with the current and future uses of genome scale constraint based metabolic modeling to further this aim.

Altered Adhesion and Migration of Human Mesenchymal Stromal Cells under Febrile Temperature Stress Involves NF-κβ Pathway

Mesenchymal stromal cells (MSCs) are clinically beneficial for regenerative treatment of chronic inflammation and autoimmune disorders. However, to attain maximum efficacy from the transplanted MSCs, evaluation of its interaction with the microenvironment, becomes critical. Fever being an important hallmark of inflammation, we investigated the effect of febrile temperature stress on adhesion and migration of umbilical cord-derived MSCs. 40 °C-exposure altered cellular morphology with significant cell flattening, delayed cell-matrix de-adhesion response and slower migration of MSCs, accompanied by suppressed directionality ratio and cell trajectory. Corresponding to the observed changes, mRNA expression of extracellular matrix genes like COLs and VTN were upregulated, while matrix metalloproteinase MMP-1, showed a significant downregulation. NF-κβ pathway inhibition at 40 °C, led to reversal of gene expression pattern, cell spreading, de-adhesion dynamics and migration rate. Independent knockdown of p65 and p53 at 40 °C indicated inhibitory role of p65/p53/p21 axis in regulation of MMP-1 expression. P21 inhibits JNK activity, and JNK pathway inhibition at 40 °C resulted in further downregulation of MMP-1. Hence, our study provides the first evidence of cell migration getting adversely affected in MSCs under elevated temperature stress due to an inverse relationship between p65/p53/p21 and MMP1 with a possible involvement of the JNK pathway.

The Impact of Cell-Expansion and Inflammation on The Immune-Biology of Human Adipose Tissue-Derived Mesenchymal Stromal Cells

Background: As a cell-based therapeutic, AT-MSCs need to create an immuno-reparative environment appropriate for tissue repair. In the presence of injury, MSCs may have to proliferate and face inflammation. Clinical application requires repeated administrations of a high number of cells with a well-established immune profile. Methods: We have established an immuno-comparative screening by determining the expression of 28 molecules implicated in immune regulation. This screening was performed during cell-expansion and inflammatory priming of AT-MSCs. Results: Our study confirms that AT-MSCs are highly expandable and sensitive to inflammation. Both conditions have substantially modulated the expression of a panel of immunological marker. Specifically, CD34 expression was substantially decreased upon cell-passaging. HLA-ABC, CD40 CD54, CD106, CD274 and CD112 were significantly increased by inflammation. In vitro cell-expansion also significantly altered the expression profile of HLA-DR, CD40, CD62L, CD106, CD166, HLA-G, CD200, HO-1, CD155 and ULBP-3. Conclusion: This study points out the response and characteristics of MSCs following expansion and inflammatory priming. It will strength our knowledge about the molecular mechanisms that may improve or hamper the therapeutic potential of MSCs. These immunological changes need to be further characterized to guarantee a safe cellular product with consistent quality and high therapeutic efficacy.

Therapeutic Potential of Mesenchymal Stem Cells for Cancer Therapy

Mesenchymal stem cells (MSCs) are among the most frequently used cell type for regenerative medicine. A large number of studies have shown the beneficial effects of MSC-based therapies to treat different pathologies, including neurological disorders, cardiac ischemia, diabetes, and bone and cartilage diseases. However, the therapeutic potential of MSCs in cancer is still controversial. While some studies indicate that MSCs may contribute to cancer pathogenesis, emerging data reported the suppressive effects of MSCs on cancer cells. Because of this reality, a sustained effort to understand when MSCs promote or suppress tumor development is needed before planning a MSC-based therapy for cancer. Herein, we provide an overview on the therapeutic application of MSCs for regenerative medicine and the processes that orchestrates tissue repair, with a special emphasis placed on cancer, including central nervous system tumors. Furthermore, we will discuss the current evidence regarding the double-edged sword of MSCs in oncological treatment and the latest advances in MSC-based anti-cancer agent delivery systems.

Cardiac Nestin+ Mesenchymal Stromal Cells Enhance Healing of Ischemic Heart through Periostin-Mediated M2 Macrophage Polarization

Mesenchymal stromal cells (MSCs) show potential for treating cardiovascular diseases, but their therapeutic efficacy exhibits significant heterogeneity depending on the tissue of origin. This study sought to identify an optimal source of MSCs for cardiovascular disease therapy. We demonstrated that Nestin was a suitable marker for cardiac MSCs (Nes⁺cMSCs), which were identified by their self-renewal ability, tri-lineage differentiation potential, and expression of MSC markers. Furthermore, compared with bone marrow-derived MSCs (Nes⁺bmMSCs) or saline-treated myocardial infarction (MI) controls, intramyocardial injection of Nes⁺cMSCs significantly improved cardiac function and decreased infarct size after acute MI (AMI) through paracrine actions, rather than transdifferentiation into cardiac cells in infarcted heart. We further revealed that Nes⁺cMSC treatment notably reduced pan-macrophage infiltration while inducing macrophages toward an anti-inflammatory M2 phenotype in ischemic myocardium. Interestingly, Periostin, which was highly expressed in Nes⁺cMSCs, could promote the polarization of M2-subtype macrophages, and knockdown or neutralization of Periostin remarkably reduced the therapeutic effects of Nes⁺cMSCs by decreasing M2 macrophages at lesion sites. Thus, the present work systemically shows that Nes⁺cMSCs have greater efficacy than do Nes⁺bmMSCs for cardiac healing after AMI, and that this occurs at least partly through Periostin-mediated M2 macrophage polarization.

Combinatorial conditioning of adipose derived-mesenchymal stem cells enhances their neurovascular potential: Implications for intervertebral disc degeneration

BACKGROUND

Mesenchymal stem cells (MSCs) are becoming an increasingly attractive option for regenerative therapies due to their availability, self-renewal capacity, multilineage potential, and anti-inflammatory properties. Clinical trials are underway to test the efficacy of stem cell-based therapies for the repair and regeneration of the degenerate intervertebral disc (IVD), a major cause of back pain. Recently, both bone marrow-derived MSCs and adipose-derived stem cells (ASCs) have been assessed for IVD therapy but there is a lack of knowledge surrounding the optimal cell source and the response of transplanted cells to the low oxygen, pro-inflammatory niche of the degenerate disc. Here, we investigated several neurovascular factors from donor-matched MSCs and ASCs that may potentiate the survival and persistence of sensory nerve fibers and blood vessels present within painful degenerate discs and their regulation by oxygen tensions and inflammatory cytokines.

METHODS

Donor-matched ASCs and MSCs were conditioned with either IL-1β or TNFα under normoxic (21% O2) or hypoxic (5% O2) conditions. Expression and secretion of several potent neurovascular factors were assessed using qRT-PCR and human magnetic Luminex assay.

RESULTS

ASCs and MSCs expressed constitutive levels of key neurotrophic factors; and stimulation of ASCs with hypoxia triggered increased secretion of both angiogenic factors (Ang-2 and VEGF-A) and neurotrophic (NGF and NT-3) compared to MSCs. We also report increased transcriptional regulation of pain-associated neuropeptides in hypoxia stimulated ASCs compared to those in normoxic conditions. We demonstrate transcriptional and translational upregulation of NGF, NT-3, Ang-1, and FGF-2 in response to cytokines in ASCs in 21% and 5% O2.

CONCLUSIONS

This work highlights fundamental differences between the neurovascular secretome of donor-matched ASCs and MSCs, demonstrating the importance of cell-selection for tissue specific regeneration to reduce ectopic sensory nerve and blood vessel survival and improve patient outcomes.

Autologous Micro-Fragmented Adipose Tissue as Stem Cell-Based Natural Scaffold for Cartilage Defect Repair

Osteoarthritis (OA) poses a tough challenge worldwide. Adipose-derived stem cells (ASCs) have been proved to play a promising role in cartilage repair. However, enzymatic digestion, ex vivo culture and expansion, with significant senescence and decline in multipotency, limit their application. The present study was designed to obtain micro-fragmented adipose tissue (MFAT) through gentle mechanical force and determine the effect of this stem cell-based natural scaffold on repair of full-thickness cartilage defects. In this study, ASCs sprouted from MFAT were characterized by multi-differentiation induction and flow cytometry. Scratch and transwell migration assays were operated to determine whether MFAT could promote migration of chondrocytes in vitro. In a rat model, cartilage defects were created on the femoral groove and treated with intra-articular injection of MFAT or PBS for 6 weeks and 12 weeks (n = 12). At the time points, the degree of cartilage repair was evaluated by histological staining, immunohistochemistry and scoring, respectively. Two unoperated age-matched animals served as native controls. ASCs derived from MFAT possessed properties to differentiate into adipocytes, osteocytes and chondrocytes, with expression of mesenchymal stem cell markers (CD29, 44, 90) and no expression of hematopoietic markers (CD31, 34, 45). In addition, MFAT could significantly promote migration of chondrocytes. MFAT-treated defects showed improved macroscopic appearance and histological evaluation compared with PBS-treated defects at both time points. After 12 weeks of treatment, MFAT-treated defects displayed regular surface, high amount of hyaline cartilage, intact subchondral bone reconstruction and corresponding formation of type I, II, and VI collagen, which resembled the normal cartilage. This study demonstrates the efficacy of MFAT on cartilage repair in an animal model for the first time, and the utility of MFAT as a ready-to-use therapeutic alternative to traditional stem cell therapy.

FoxO transcription factors modulate autophagy and proteoglycan 4 in cartilage homeostasis and osteoarthritis

Aging is a main risk factor for osteoarthritis (OA). FoxO transcription factors protect against cellular and organismal aging, and FoxO expression in cartilage is reduced with aging and in OA. To investigate the role of FoxO in cartilage, Col2Cre-FoxO1, 3, and 4 single knockout (KO) and triple KO mice (Col2Cre-TKO) were analyzed. Articular cartilage in Col2Cre-TKO and Col2Cre-FoxO1 KO mice was thicker than in control mice at 1 or 2 months of age. This was associated with increased proliferation of chondrocytes of Col2Cre-TKO mice in vivo and in vitro. OA-like changes developed in cartilage, synovium, and subchondral bone between 4 and 6 months of age in Col2Cre-TKO and Col2Cre-FoxO1 KO mice. Col2Cre-FoxO3 and FoxO4 KO mice showed no cartilage abnormalities until 18 months of age when Col2Cre-FoxO3 KO mice had more severe OA than control mice. Autophagy and antioxidant defense genes were reduced in Col2Cre-TKO mice. Deletion of FoxO1/3/4 in mature mice using Aggrecan(Acan)-CreERT2 (AcanCreERT-TKO) also led to spontaneous cartilage degradation and increased OA severity in a surgical model or treadmill running. The superficial zone of knee articular cartilage of Col2Cre-TKO and AcanCreERT-TKO mice exhibited reduced cell density and markedly decreased Prg4 In vitro, ectopic FoxO1 expression increased Prg4 and synergized with transforming growth factor-β stimulation. In OA chondrocytes, overexpression of FoxO1 reduced inflammatory mediators and cartilage-degrading enzymes, increased protective genes, and antagonized interleukin-1β effects. Our observations suggest that FoxO play a key role in postnatal cartilage development, maturation, and homeostasis and protect against OA-associated cartilage damage.

In Vitro Angiogenic Properties of Plasmid DNA Encoding SDF-1α and VEGF165 Genes

The stromal-derived factor-1 alpha (SDF-1α) and vascular endothelial growth factor (VEGF) play an important role in angiogenesis and exert a significant trophic function. SDF-1α is a chemoattractant for endothelial progenitor cells derived from bone marrow and promotes new blood vessel formation. VEGF regulates all types of vascular growth, stimulates angiogenesis, and is involved in the induction of lymphangiogenesis. The possibility of using these growth factors for regenerative medicine is currently under investigation. The angiogenic potential of a pBud-SDF-1α-VEGF165 bicistronic plasmid construct which simultaneously encodes VEGF165 and SDF-1α genes cDNA was evaluated in this study. The conditioned medium collected from HEK293T cells transfected with the pBud-SDF-1α-VEGF165 plasmid was shown to stimulate the formation of capillary-like structures by human umbilical vein-derived endothelial cells (HUVEC) on Matrigel and to increase the proliferative activity of these cells in vitro. Thus, the pBud-SDF-1α-VEGF165 plasmid exhibits angiogenic properties in cell cultures in vitro. As interest in the development of non-viral techniques for regenerative medicine increases, this plasmid which simultaneously expresses VEGF165 and SDF-1α may provide a platform for advanced methods of stimulating therapeutic angiogenesis.

Biophysical Characterization and Drug Delivery Potential of Exosomes from Human Wharton's Jelly-Derived Mesenchymal Stem Cells

Cell-derived exosomes (30-200 nm) as biological "nanocarriers" have attracted a great deal of interest for therapeutic applications due to their ability to internalize in in vivo biological systems (i.e., cells). Although they can be harvested from various sources including stem cells, yet an appropriate isolation and characterization protocol to obtain "pure" exosomal population is needed. For potential clinical applications, understanding the functional ability of exosomes and their purity, that is, free from microvesicles, apoptotic bodies, and protein aggregates, is a pre-requisite. To achieve high purity and yield of exosomes from human Wharton's jelly-derived mesenchymal stem cells (hWJ-MSCs) in the size range of 30-200 nm, we have performed and compared three isolation procedures: ultracentrifugation (UC), sucrose cushion (SC), and commercially available reagent (CR). The isolated exosomes were characterized using nanoparticle tracking analysis (NTA), field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM). Furthermore, to understand the therapeutic potential of the hWJ-MSC-derived exosomes (hWJ-ME) to target pancreatic tumor cells, the internalization efficacy has been evaluated on the MiaPaCa-2 cell lines using confocal microscopy and flow cytometry. The NTA results showed sucrose cushion to be an optimal method for exosome isolation with high purity (86.8%), as compared to UC (40.5%; p = 0.050) and CR (38%; p = 0.050). Optical analysis by FESEM and AFM revealed that SC-isolated exosomes presented a spherical morphology, whereas UC- and CR-isolated exosomes exhibited an uneven morphology. Furthermore, the data from confocal images and flow cytometry showed that hWJ-ME were internalized by MiaPaCa-2, demonstrating the feasibility of exosomes as a "potential nanocarrier". Thus, our study suggests that a combination of NTA (yield), AFM (dimensions), and FESEM (morphology and topography) could provide sensitive biophysical characterization of hWJ-ME. In the future, enriched exosomes could be used as a delivery vehicle to transport target-specific drugs or gene-silencing constructs to tumors.

Nature vs. Nurture: Defining the Effects of Mesenchymal Stromal Cell Isolation and Culture Conditions on Resiliency to Palmitate Challenge

As MSC products move from early development to clinical translation, culture conditions shift from xeno- to xeno-free systems. However, the impact of isolation and culture-expansion methods on the long-term resiliency of MSCs within challenging transplant environments is not fully understood. Recent work in our lab has shown that palmitate, a saturated fatty acid elevated in the serum of patients with obesity, causes MSCs to convert from an immunosuppressive to an immunostimulatory state at moderate to high physiological levels. This demonstrated that metabolically-diseased environments, like obesity, alter the immunomodulatory efficacy of healthy donor MSCs. In addition, it highlighted the need to test MSC efficacy not only in ideal conditions, but within challenging metabolic environments. To determine how the choice of xeno- vs. xeno-free media during isolation and expansion would affect future immunosuppressive function, umbilical cord explants from seven donors were subdivided and cultured within xeno- (fetal bovine serum, FBS) or xeno-free (human platelet lysate, PLT) medias, creating 14 distinct MSC preparations. After isolation and primary expansion, umbilical cord MSCs (ucMSC) were evaluated according to the ISCT minimal criteria for MSCs. Following baseline characterization, ucMSC were exposed to physiological doses of palmitate and analyzed for metabolic health, apoptotic induction, and immunomodulatory potency in co-cultures with stimulated human peripheral blood mononuclear cells. The paired experimental design (each ucMSC donor grown in two distinct culture environments) allowed us to delineate the contribution of inherent (nature) vs. environmentally-driven (nurture) donor characteristics to the phenotypic response of ucMSC during palmitate exposure. Culturing MSCs in PLT-media led to more consistent growth characteristics during the isolation and expansion for all donors, resulting in faster doubling times and higher cell yields compared to FBS. Upon palmitate challenge, PLT-ucMSCs showed a higher susceptibility to palmitate-induced metabolic disturbance, but less susceptibility to palmitate-induced apoptosis. Most striking however, was that the PLT-ucMSCs resisted the conversion to an immunostimulatory phenotype better than their FBS counterparts. Interestingly, examining MSC suppression of PBMC proliferation at physiologic doses of palmitate magnified the differences between donors, highlighting the utility of evaluating MSC products in stress-based assays that reflect the challenges MSCs may encounter post-transplantation.

The effects of graphene and mesenchymal stem cells in cutaneous wound healing and their putative action mechanism

This study provides a review of the therapeutic potential of graphene dressing scaffolds and mesenchymal stem cells (MSCs) and their synergistic effects with respect to cutaneous wound healing. This study also considers their putative action mechanism based on the antibacterial, immunomodulating, angiogenic, matrix remodeling effects of materials belonging to the graphene family and MSCs during the wound healing process. In addition, this study discusses the cytocompatibility of graphene, its uses as a platform for skin substitutes, the properties it possesses with respect to providing protection against microbial invasion as well as strategies aimed at minimizing the chance of the occurrence of sepsis. MSCs are capable of secreting several factors that exert a therapeutic impact on reparative processes and tissue regeneration. In light of experiments conducted to date, graphene combined with MSCs appears to have the potential to enhance both the wound healing process and infection control at the injury site.

In Vitro Anticancer Activity of Extracellular Vesicles (EVs) Secreted by Gingival Mesenchymal Stromal Cells Primed with Paclitaxel

Interdental papilla are an interesting source of mesenchymal stromal cells (GinPaMSCs), which are easy to isolate and expand in vitro. In our laboratory, GinPaMSCs were isolated, expanded, and characterized by studying their secretome before and after priming with paclitaxel (PTX). The secretome of GinPaMSCs did not affect the growth of cancer cell lines tested in vitro, whereas the secretome of GinPaMSCs primed with paclitaxel (GinPaMSCs/PTX) exerted a significant anticancer effect. GinPaMSCs were able to uptake and then release paclitaxel in amounts pharmacologically effective against cancer cells, as demonstrated in vitro by the direct activity of GinPaMSCs/PTX and their secretome against both human pancreatic carcinoma and squamous carcinoma cells. PTX was associated with extracellular vesicles (EVs) secreted by cells (EVs/PTX), suggesting that PTX is incorporated into exosomes during their biogenesis. The isolation of mesenchymal stromal cells (MSCs) from gingiva is less invasive than that from other tissues (such as bone marrow and fat), and GinPaMSCs provide an optimal substrate for drug-priming to obtain EVs/PTX having anticancer activity. This research may contribute to develop new strategies of cell-mediated drug delivery by EVs that are easy to store without losing function, and could have a superior safety profile in therapy.

The Transplantation of hBM-MSCs Increases Bone Neo-Formation and Preserves Hearing Function in the Treatment of Temporal Bone Defects - on the Experience of Two Month Follow Up

Temporal bone reconstruction is a persisting problem following middle ear cholesteatoma surgery. Seeking to advance the clinical transfer of stem cell therapy we attempted the reconstruction of temporal bone using a composite bioartificial graft based on a hydroxyapatite bone scaffold combined with human bone marrow-derived mesenchymal stromal cells (hBM-MSCs). The aim of this study was to evaluate the effect of the combined biomaterial on the healing of postoperative temporal bone defects and the preservation of physiological hearing functions in a guinea pig model. The treatment's effect could be observed at 1 and 2 months after implantation of the biomaterial, as opposed to the control group. The clinical evaluation of our results included animal survival, clinical signs of an inflammatory response, and exploration of the tympanic bulla. Osteogenesis, angiogenesis, and inflammation were evaluated by histopathological analyses, whereas hBM-MSCs survival was evaluated by immunofluorescence assays. Hearing capacity was evaluated by objective audiometric methods, i.e. auditory brainstem responses and otoacoustic emission. Our study shows that hBM-MSCs, in combination with hydroxyapatite scaffolds, improves the repair of bone defects providing a safe and effective alternative in their treatment following middle ear surgery due to cholesteatoma.

Beneficial effects of mesenchymal stem cells on adult porcine cardiomyocytes in non-contact co-culture

Mesenchymal stem cells (MSCs) have been reported to improve survival of cardiomyocytes (CMCs) and overall regeneration of cardiac tissue. Despite promising preclinical results, interactions of MSCs and CMCs, both direct and indirect, remain unclear. In this study, porcine bone marrow MSCs and freshly isolated porcine primary adult CMCs were used for non-contact co-culture experiments. Morphology, viability and functional parameters of CMCs were measured over time and compared between CMCs cultured alone and CMCs co-cultured with MSCs. In non-contact co-culture, MSCs improved survival of CMCs. CMCs co-cultured with MSCs maintained CMCs morphology and viability in significantly higher percentage than CMCs cultured alone. In viable CMCs, mitochondrial respiration was preserved in both CMCs cultured alone and in CMCs co-cultured with MSCs. Comparison of cellular contractility and calcium handling, measured in single CMCs, revealed no significant differences between viable CMCs from co-culture and CMCs cultured alone. In conclusion, non-contact co-culture of porcine MSCs and CMCs improved survival of CMCs with a sufficient preservation of functional and mitochondrial parameters.

Comparative evaluation of mesenchymal stromal cells from umbilical cord and amniotic membrane in xeno-free conditions

BACKGROUND

Within the past years, umbilical cord (UC) and amniotic membrane (AM) expanded in human platelet lysate (PL) have been found to become increasingly candidate of mesenchymal stromal cells (MSCs) in preclinical and clinical studies. Different sources of MSCs have different properties, and lead to different therapeutic applications. However, the similarity and differences between the AMMSCs and UCMSCs in PL remain unclear.

RESULTS

In this study, we conduct a direct head-to-head comparison with regard to biological characteristics (morphology, immunophenotype, self-renewal capacity, and trilineage differentiation potential) and immunosuppression effects of AMMSCs and UCMSCs expanded in PL. Our results indicated that AMMSCs showed similar morphology, immunophenotype, proliferative capacity and colony efficiency with UCMSCs. Moreover, no significantly differences in osteogenic, chondrogenic and adipogenic differentiation potential were observed between the two types of cells. However, AMMSCs exhibited higher PGE₂ expression and IDO activity compared with UCMSCs when primed by IFN-γ and (or) TNF-α induction, and AMMSCs showed a higher inhibitory effect on PBMCs proliferation than UCMSCs.

CONCLUSION

The results suggest that AMMSCs expanded in PL showed similar morphology, immunophenotype, self-renewal capacity, and trilineage differentiation potential with UCMSCs. However, AMMSCs possessed superior immunosuppression effects in comparison with UCMSCs. These results suggest that AMMSCs in PL might be more suitable than UCMSCs for treatment of immune diseases. This work provides a novel insight into choosing the appropriate source of MSCs for treatment of immune diseases.

Comparative study of mesenchymal stem cells from rat bone marrow and adipose tissue

Several therapeutic products based on mesenchymal stem cells (MSCs) have been translated into clinical applications. MSCs should undergo in vitro culture before a sufficient quantity can be achieved. Hence, both expansion kinetics and the biological characteristics of derived cells from primary culture are pertinent to their applications. In the present study, MSCs were isolated from rat bone marrow and adipose tissue (designated as bMSCs and aMSCs, respectively) and cells were comparatively analyzed regarding cell morphology, proliferation, colony formation, differentiation potential, and immunophenotype following the long-term subculture. No apparent differences could be noticed concerning the morphology between bMSCs and aMSCs. The long-term subculture made both types of cells smaller, weakened their colony-forming ability, and stimulated the proliferation rate. However, bMSCs demonstrated better proliferation and colony-forming ability than aMSCs. No significant difference was observed about the expression of some immunophenotypes (i.e. CD29+/CD90+/CD34-/CD45-) regardless of cell types or population doublings. Notably, bMSCs, but not aMSCs, maintained the differentiation potential well after the long-term subculture. The present study demonstrates that MSCs derived from different tissues can be well expanded for the long term, although cells display gradually declined self-renewal and differentiation potentials to different extents depending on the tissue origins.

Chromatin accessibility identifies diversity in mesenchymal stem cells from different tissue origins

Mesenchymal stem cells (MSCs), which can differentiate into tri-lineage (osteoblast, adipocyte, and chondrocyte) and suppress inflammation, are promising tools for regenerative medicine. MSCs are phenotypically diverse based on their tissue origins. However, the mechanisms underlying cell-type-specific gene expression patterns are not fully understood due to the lack of suitable strategy to identify the diversity. In this study, we investigated gene expression programs and chromatin accessibilities of MSCs by whole-transcriptome RNA-seq analysis and an assay for transposase-accessible chromatin using sequencing (ATAC-seq). We isolated MSCs from four tissues (femoral and vertebral bone marrow, adipose tissue, and lung) and analysed their molecular signatures. RNA-seq identified the expression of MSC markers and both RNA-seq and ATAC-seq successfully clustered the MSCs based on their tissue origins. Interestingly, clustering based on tissue origin was more accurate with chromatin accessibility signatures than with transcriptome profiles. Furthermore, we identified transcription factors potentially involved in establishing cell-type specific chromatin structures. Thus, epigenome analysis is useful to analyse MSC identity and can be utilized to characterize these cells for clinical use.

Human amniotic fluid stem cells have a unique potential to accelerate cutaneous wound healing with reduced fibrotic scarring like a fetus

Adult wound healing can result in fibrotic scarring (FS) characterized by excess expression of myofibroblasts and increased type I/type III collagen expression. In contrast, fetal wound healing results in complete regeneration without FS, and the mechanism remains unclear. Amniotic fluid cells could contribute to scar-free wound healing, but the effects of human amniotic fluid cells are not well characterized. Here, we determined the effect of human amniotic fluid stem cells (hAFS) on FS during wound healing. Human amniotic fluid was obtained by amniocentesis at 15-17 weeks of gestation. CD117-positive cells were isolated and defined as hAFS. hAFS (1 × 10⁶) suspended in PBS or cell-free PBS were injected around wounds created in the dorsal region of BALB/c mice. Wound size was macroscopically measured, and re-epithelialization in the epidermis, granulation tissue area in the dermis and collagen contents in the regenerated wound were histologically analyzed. The ability of hAFS to engraft in the wound was assessed by tracking hAFS labeled with PKH-26. hAFS fulfilled the minimal criteria for mesenchymal stem cells. hAFS injection into the wound accelerated wound closure via enhancement of re-epithelialization with less FS. The process was characterized by lower numbers of myofibroblasts and higher expression of type III collagen. Finally, transplanted hAFS were clearly observed in the dermis until day 7 implying that hAFS worked in a paracrine manner. hAFS can function in a paracrine manner to accelerate cutaneous wound healing, producing less FS, a process resembling fetal wound healing.

Mesenchymal stem/stromal cells genetically engineered to produce vascular endothelial growth factor for revascularization in wound healing and ischemic conditions

Mesenchymal stem/stromal cells (MSCs) may be able to improve ischemic conditions as they can actively seek out areas of low oxygen and secrete proangiogenic factors. In more severe trauma and chronic cases, however, cells alone may not be enough. Therefore, we have combined the stem cell and angiogenic factor approaches to make a more potent therapy. We developed an engineered stem cell therapy product designed to treat critical limb ischemia that could also be used in trauma-induced scarring and fibrosis where additional collateral blood flow is needed following damage to and blockage of the primary vessels. We used MSCs from normal human donor marrow and engineered them to produce high levels of the angiogenic factor vascular endothelial growth factor (VEGF). The MSC/VEGF product has been successfully developed and characterized using good manufacturing practice (GMP)-compliant methods, and we have completed experiments showing that MSC/VEGF significantly increased blood flow in the ischemic limb of immune deficient mice, compared to the saline controls in each study. We also performed safety studies demonstrating that the injected product does not cause harm and that the cells remain around the injection site for more than 1 month after hypoxic preconditioning. An on-demand formulation system for delivery of the product to clinical sites that lack cell processing facilities is in development.

Morpho-Functional Characteristics of Bone Marrow Multipotent Mesenchymal Stromal Cells after Activation or Inhibition of Epidermal Growth Factor and Toll-Like Receptors or Treatment with DNA Intercalator Cisplatin

This study is aimed to reveal morphological and functional changes in multipotent mesenchymal stromal cells (MSCs) isolated from the rat bone marrow after: (i) activation of Toll-like receptors (TLRs) with teichoic acid (TA), (ii) impact on epidermal growth factor (EGF) receptors with activator EGF or inhibitor Herceptin, and (iii) treatment with DNA intercalator Cisplatin. According to our results, TA and EGF cause an increase in the synthesis of glycosaminoglycans, c-Myc content, and protein in the MSC cytoplasm. It was observed that the cell population in G0 phase decreased and the cell population in G1 phase increased, when compared with control. At the same time, the cell population with a higher nuclear-cytoplasmic ratio (NCR) in S and G2 phases also increased. This indicates the manifestation of the MSC mesenchymal phenotype, exhibiting indirect metabolic signs of the regenerative potential increase. In other experiments, Herceptin was shown to suppress only the stemness signs of MSCs, while Cisplatin seriously affected cell viability in general, reducing synthetic and proliferative activities and causing cell morphology disturbances. © 2018 International Society for Advancement of Cytometry.

Mesenchymal Stromal Cells Based Therapy in Systemic Sclerosis: Rational and Challenges

Systemic Sclerosis (SSc) is a rare chronic disease, related to autoimmune connective tissue diseases such as Systemic Lupus Erythematosus and Sjögren's Syndrome. Although its clinical heterogeneity, main features of the disease are: extensive tissue fibrosis with increase matrix deposition in skin and internal organ, microvascular alterations and activation of the immune system with autoantibodies against various cellular antigens. In the diffuse cutaneous scleroderma subtype, the disease is rapidly progressive with a poor prognosis, leading to failure of almost any internal organ, especially lung which is the leading cause of death. Primary trigger is unknown but may involve an immune process against mesenchymal cells in a genetically receptive host. Pathophysiology reveals a pivotal role of fibrosis and inflammation alterations implicating different cell subtypes, cytokines and growth factors, autoantibodies and reactive oxygen species. Despite improvement, the overall survival of SSc patients is still lower than that of other inflammatory diseases. Recommended drugs are agents capable of modulating fibrotic and inflammatory pathways. Cellular therapy has recently emerged as a credible option. Besides autologous hematopoietic stem cell transplantation which demonstrated remarkable improvement, mesenchymal stromal cells (MSCs) represent promising therapeutic candidates. Indeed, these cells possess anti-inflammatory, antiproliferative, antifibrotic, and immunomodulary properties especially by secreting a large panel of bioactive molecules, addressing the most important key points of the SSc. In addition, these cells are very sensitive to their environment and are able to modulate their activity according to the pathophysiological context in which they are located. Autologous or allogeneic MSCs from various sources have been tested in many trials in different auto-immune diseases such as multiple sclerosis, Crohn's disease or systemic lupus erythematosus. They are characterized by a broad availability and no or low acute toxicity. However, few randomized prospective clinical trials were published and their production under ATMP regulatory procedures is complex and time-consuming. Many aspects have still to be addressed to ascertain their potential as well as the potential of their derived products in the management of SSc, probably in association with other therapies.

Comparative Study on the Application of Mesenchymal Stromal Cells Combined with Tricalcium Phosphate Scaffold into Femoral Bone Defects

This prospective study sought to evaluate the healing quality of implanted ultraporous β-tricalcium phosphate sown with expanded autologous mesenchymal stromal cells (MSCs) into femoral defects during revision hip arthroplasty. A total of 37 osseous defects in 37 patients were treated and evaluated concerning bone regeneration. Nineteen subjects received β-tricalcium phosphate graft material serving as a carrier of expanded autologous MSCs (the trial group A), nine subjects received β-tricalcium phosphate graft material only (the study group B) and nine subjects received cancellous allografts only (the control group C). Clinical and radiographic evaluations were scheduled at 6 weeks, 3, 6, and 12 months post-operatively, and performed at the most recent visit as well. All observed complications were recorded during follow-up to assess the use of an ultraporous β-tricalcium phosphate synthetic graft material combined with expanded MSCs in bone defect repair. The resulting data from participants with accomplished follow-up were processed and statistically evaluated with a Freeman–Halton modification of the Fischer’s exact test, a P < 0.05 value was considered to be significant. Whereas no significant difference was observed between the trial group A with β-tricalcium phosphate synthetic graft material serving as a carrier of expanded autologous MSCs and control group C with cancellous impaction allografting in terms of the bone defect healing, significant differences were documented between the study group B with β-tricalcium phosphate graft material only and control group C. Regarding adverse effects, six serious events were recorded during the clinical trial with no causal relationship to the cell product. β-tricalcium phosphate synthetic graft material serving as a carrier of expanded autologous MSCs appears safe and promotes the healing of bone defects in a jeopardized and/or impaired microenvironment. This clinical trial was registered at the EU Clinical Trials Register before patient recruitment (Registration number: EudraCT number 2012-005599-33; Date of registration: 2013-02-04).

Mesenchymal stem cells derived from human iPS cells via mesoderm and neuroepithelium have different features and therapeutic potentials

Mesenchymal stem cells (MSCs) isolated from adult human tissues are capable of proliferating in vitro and maintaining their multipotency, making them attractive cell sources for regenerative medicine. However, the availability and capability of self-renewal under current preparation regimes are limited. Induced pluripotent stem cells (iPSCs) now offer an alternative, similar cell source to MSCs. Herein, we established new methods for differentiating hiPSCs into MSCs via mesoderm-like and neuroepithelium-like cells. Both derived MSC populations exhibited self-renewal and multipotency, as well as therapeutic potential in mouse models of skin wounds, pressure ulcers, and osteoarthritis. Interestingly, the therapeutic effects differ between the two types of MSCs in the disease models, suggesting that the therapeutic effect depends on the cell origin. Our results provide valuable basic insights for the clinical application of such cells.

From "Bench to Bedside": Current Advancement on Large-Scale Production of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are the primary cell source in cell therapy and regenerative medicine due to its extraordinary self-renewing capacity and multilineage differentiation potential. Clinical trials involving MSCs are being conducted in a range of human diseases and the number of registered cases is continuously increasing. However, a wide gap exists between the number of MSCs obtainable from the donor site and the number required for implantation to damage tissues, and also between MSC scalability and MSC phenotype stability. The clinical translation of MSCs necessitates a scalable expansion bioprocess for the biomanufacturing of therapeutically qualified cells. This review presents current achievements for expansion of MSCs. Issues involving culture condition modification, bioreactor systems, as well as microcarrier and scaffold platforms for optimal MSC systems are discussed. Most importantly, the gap between current MSC expansion and clinical application, as well as outbreak directions for the future are discussed. The present systemic review will bring new insights into future large-scale MSC expansion and clinical application.